Photography using a silver halide has been most widely utilized, since the photographic characteristics thereof such as sensitivity, gradation control, etc., are superior to those of other photographic systems such as electrophotography or a diazo process. Recently, an improved photographic technique has been developed capable of simply and rapidly forming an image, where image formation using a silver halide-containing light-sensitive material is carried out by means of a dry process under heat instead of a conventional wet process using a developing agent or the like. Such heat developable light-sensitive materials using silver halides are well known in this technical field.
Various heat developable light-sensitive materials and processes for their use are described, for example, in Shashin Kogaku no Kiso, pp. 553-555 (Corona Co., 1979); Eizo Joho (April, 1978), page 40; Neblett's Handbook of Photography and Reprography, pp. 32-33 (7th Ed., Van Nostrand Reinhold Company).
Many processes have been proposed for formation of color images in a dry system, for example, those described in West German Patent Application (OLS) Nos. 3,215,485 and 3,217,853, European Pat. Nos. 66,282, 67,455, 79,056 and 76,492. These conventional materials, however, have several disadvantages. One is the commercial disadvantage that a photographic element and a dye fixing element are formed on separate supports and thus two supports are required. Another disadvantage is that an additional step is required in which the photographic element and the dye fixing element are lapped accurately after development. Still another disadvantage is that a long time is required for completing the formation of images.